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A034887 Number of digits in 2^n. 14
1, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 22 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

The sequence consists of the positive integers, each appearing 3 or 4 times. - M. F. Hasler, Oct 08 2016

LINKS

T. D. Noe, Table of n, a(n) for n = 0..10000

Eric Weisstein's World of Mathematics, Mersenne Number

FORMULA

a(n) = floor(n*log(2)/log(10)) + 1. E.g., a(10)=4 because 2^10 = 1024 and floor(10*log(2)/log(10) + 1 = 3 + 1 = 4. - Jaap Spies, Dec 11 2003

a(n) = A055642(2^n) = A055642(A000079(n)).

MAPLE

seq(floor(n*ln(2)/ln(10))+1, n=0..100); # Jaap Spies, Dec 11 2003

MATHEMATICA

Table[Length[IntegerDigits[2^n]], {n, 0, 100}] (* T. D. Noe, Feb 11 2013 *)

PROG

(MAGMA) [#Intseq(2^n): n in [0..100] ]; // Vincenzo Librandi, Jun 23 2015

(PARI) A034887(n)=n*log(2)\log(10)+1 \\ or: { a(n)=#digits(1<<n) }. - M. F. Hasler, Oct 08 2016

CROSSREFS

Cf. A055253, A055254.

Cf. A000079, A055642.

See A125117 for the sequence of first differences.

Sequence in context: A222642 A081832 * A192543 A082964 A209356 A099741

Adjacent sequences:  A034884 A034885 A034886 * A034888 A034889 A034890

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane

STATUS

approved

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Last modified December 3 18:47 EST 2016. Contains 278745 sequences.